use SQL::Builder::Select;

$select = new SQL::Builder::Select;

$select->where_eq_or('col1', 'col2');

$where = $select->return_where();


$select = new SQL::Builder::Select;

$select->column('*');
$select->table('table');

$select->where( $where );
$select->where_ne_or('col1', 'col2');
$select->where_logic('w AND o');

print $select->return();